Maureen Johnson is a graduate of the University of Delaware. Prior to that she attended an all-girl Catholic preparatory high school. In the short period between her undergraduate and graduate careers, Johnson worked in Philadelphia, London, and New York City. She was the literary manager of a Philadelphia theater company, a waitress in a theme restaurant, a secretary, a bartender in Piccadilly, and an occasional performer. She studied both writing and theatrical dramaturgy at Columbia University, where she received her MFA in Writing.

Johnson is part of an unofficial group of well-established YA authors in New York City, including Scott Westerfeld, John Green, Justine Larbalestier, Holly Black, Libba Bray, Cassandra Clare, Lauren Myracle and others. She was also an occasional participant and a "secret sister" on John and Hank Green's Brotherhood 2.0 project, and is responsible for starting the "in your pants" joke frequently used throughout the project. She briefly replaced John on the channel while he was away on paternity leave in 2010. She referred to herself as "the second prettiest Green brother."

In June 2007, Johnson's book The Bermudez Triangle was challenged by the parent of a student in Bartlesville, Oklahoma. While book challenges are not uncommon in the United States, Johnson's response on her blog is notable for its immediacy and for its call for greater transparency in the school system's challenge process. To resolve the controversy, the school board did not officially ban the book but placed it in a restricted area of the high school's library.

In September 2008, Johnson launched the political social networking community YA for Obama. The site was designed for teenagers and others who wished to support 2008 presidential candidate Barack Obama. It is hosted by Ning and includes archives of discussion forums, user-generated content such as videos and photos, and daily blog updates written by well-known YA authors such as Scott Westerfeld, Lauren Myracle, Cecily von Ziegesar, and Megan McCafferty.

Suite Scarlett, the first book in the "Suite Scarlett" series, was published by Scholastic in May 2008. The second book, Scarlett Fever, was released on February 1, 2010. Johnson is writing a sequel to her 2006 novel 13 Little Blue Envelopes, which will be titled The Last Little Blue Envelope. On November 27, 2009, Johnson became a New York Times Best Selling author when Let It Snow: Three Holiday Romances, a book she co-wrote with John Green and Lauren Myracle in 2008, reached number ten on the Children's Paperback list.

Johnson was also a scriptwriter for the Nintendo DS and PSP versions of the Harry Potter and the Half-Blood Prince video game.

Maureen Johnson is the Head of Ravenclaw for The Harry Potter Alliance.

Johnson currently resides in New York City, though she travels to the United Kingdom on a regular basis.

Standalone novels

• The Key to the Golden Firebird (2004)
• The Bermudez Triangle (2005)
• Devilish (2006)
• Girl at Sea (2007)
• Let It Snow: Three Holiday Romances (with John Green and Lauren Myracle, 2008)
• Vacations From Hell (with Libba Bray, Cassandra Clare, Claudia Gray and Sarah Mlynowski, 2009)

13 Little Blue Envelopes series

• 13 Little Blue Envelopes (2005)
• The Last Little Blue Envelope (April 26th, 2011)

Suite Scarlett series

• Suite Scarlett (2008)
• Scarlett Fever (2010)

Untitled thriller trilogy

• TBA (Summer 2011)

Essays

• "Hot Sex and Horrific Parenting in His Dark Materials" (published in The World of the Golden Compass, 2007)